To toast the pecans, use a shallow pan and bake at 300°F (148°C) in a single layer for 10-15 minutes. Stir once or twice. Cool completely before chopping.
Beat the butter for 30 seconds on medium speed. Add 1/4 cup powdered sugar and beat until combined, scraping the side as needed.
Add the water and vanilla extract, beat well. Slowly add in the flour and beat as much as you can. If it gets hard to mix, stop the mixer and use a wooden spatula. Stir in the remaining flour and chopped pecans. If needed, use your hand to mix until all ingredients are well combined.
Transfer the dough to a plastic wrap, roll it up tightly and chill for 30-60 minutes or until the dough is firm.
Preheat the oven to 325°F (160°C). Line a baking sheet with parchment paper.
Shape the dough into 1" (2.5cm) balls and place them on the baking sheet 1" (2.5cm) apart. Bake for 15 minutes or until the bottom is slightly browned. Transfer to wire rack to cool completely before dusting with powdered sugar.
Notes
This recipe is halved from the original recipe. To store the cookies, layer them between waxed paper in an air tight container. If you preferred, you can use non-toasted pecans.